How to Waterproof a Backpack

If you are an outdoors enthusiast you will probably be aware of unpredictable climates and surprise showers that can quickly leave you and the contents of your backpack sad and sodden. Waterproof backpacks are an incredibly valuable purchase if you want to ensure your belongs stay dry when you’re out and about.

When it comes to the weather, it is definitely better to be over-prepared than underprepared. After all, there is nothing worse than getting to the end of a day and realising your sleeping bag is wet through.

Waterproof backpacks can be expensive, but don’t worry. There are many alternative ways to keep your kit dry if you don’t want to splash out. We know how precious a dry pair of socks is to any adventurer, so we have put together a guide on the best ways to waterproof your backpack.

silicone waterproof spraySprays

The first preventative method you should take when waterproofing your backpack is using a water-repellent spray. Similar to the sprays used to re-proof jackets and shoes, they are a good way to add some extra protection to the material lining of your bag.

Before spraying, ensure all dirt and dust particles are removed to ensure maximum coverage. One coat should be enough, although regular re-applications are necessary.

There are a plethora of proofer sprays on the market, but our advice would be to opt for a reputable and high-quality one to reduce the risk of damaging the design of your bag with potentially harmful chemicals. Remember to always test a small inconspicuous section first to be safe, and then you’re ready to go!

Here are some of the best waterproof sprays for backpacks:

• Granger’s Performance Repel Plus – Designed for outdoor clothing as well as items like backpacks, this silicone waterproof spray has the added bonus that it is eco-friendly and odourless when applied.
• 303 Fabric Guard – A slightly pricier option, but specially designed for outdoor items like backpacks.
• Mountval Waterproofing Spray – This top-rated waterproofing spray is great for backpacks, offering versatile and breathable protection for all kinds of fabrics

Seam Sealer 

Proofing sprays will be ineffective if the seams and zippers are forgotten about. After you’ve waterproofed your bag with a spray, you’ll need to seal the seams as well.

To apply a seam sealant, first stuff your backpack so the seams and stitching are fully exposed. Cover all stitch holes with a good-quality, silicone sealant and allow to dry for at least 24-hours. Take extra care when applying sealant around buckles as zippers as this stuff can be pretty tough to get off and you do not want to risk glueing yourself out of your backpack! 

After these two steps, you should be well underway to a waterproof backpack come rain or shine.

The top-rated seam sealer for backpack waterproofing is McNett Seamgrip Seam Sealant, which comes with a brush that makes it incredibly easy to use. You can also use a tent sealer spray on your bag’s seams, as long as the fabric is compatible.

Backpack Liners

Protecting the shell of your backpack may not be enough, especially if embarking on a more adventurous trip involving kayaking or white water rafting. Liners go inside your backpack before you start packing, and are a great way to add an extra level of protection to your kit if you know there’s a high chance of the weather getting wet and wild.

Backpack liners are relatively inexpensive and can also simply opt for a plastic bag or bin liner, but these tend to be less durable and prone to tears. Although, even when using an ‘official’ sealed seam backpack liner, remember to be cautious when packing sharp objects, and check for holes beforehand.

Here are some of our top recommendations for backpack liners:

• Trekrite Waterproof Rucksack Liner – A very affordable and practical option
• Osprey Ultralight Pack Liner – A great option from a trusted backpack brand that comes in a range of different sizes

Individual Linings or Dry Bags

Separating the contents of your backpack is a great way to stay organised, and one way to do this whilst keeping things dry is to use individual waterproof dry bags. As well as compartmentalising your belongings, you can feel confident that your belongings are protected from rain or sudden submersions in water.

Ensure that the dry bags are properly closed and sealed securely and that all the air is expelled before packing so they don’t take up excess room.

If you’re looking for dry bag recommendations, here are some of our favourite options:

• Ultra Dry Waterproof Bag – A leading brand that offers a range of different sizes and colours for dry bags, often with a separate phone holder
• kuou Dry Bags Set – If you’re looking for a set of different dry bags, this brand offer five of different sizes
• Uncle Paul Boat Dry Bag – Specially designed for use on boats or around the water, you can be certain that your belongings will stay dry in this option

Rain Cover

A lot of backpacks come with their own rain cover, vbut you can easily get your hands on one if yours does not. They are thin pieces of fabric, usually nylon, that slip and secure over your bag by their elasticated edges, ensuring you have a rainproof backpack if the heavens open whilst you’re outdoors.

Rain covers offer an extra layer of protection, but they’re unlikely to be super effective in heavier downpours as they may leave sections of your bag exposed to the elements. Ensure the above steps are carried out first and use a rain cover as an extra layer of precaution or only in light showers.

If your backpack doesn’t come with its own rain cover, why not try one of these?

• LAMA Waterproof Rain Cover – For smaller backpacks, this set of rain covers is colourful and also has a reflective strip on the back, which is great if you’re out in the dark
• Trespass Waterproof Rain Cover – For larger rucksacks, this rain cover from Trespass is a reliable and affordable option

After completing all of the above, you should be well underway to having a wonderfully waterproof rucksack.

Don’ts:

• Rely on plastic bags. Although a cheap option, they will most likely cost you the luxury of warm, dry belongings. Plastic bags are prone to tears, are less durable and ultimately a less environmentally friendly option. 
• Use only one method; use them all. Depending on what scenario you are going to be in, to have the best chances of keeping your backpack and its contents dry, use all methods in conjunction with each other as none will be 100% waterproof alone. 
• Take care when packing. As mentioned above, sharp items (tent poles, knives, pegs) can rip waterproof liners or even the canvas of the backpack itself. Additionally, ensure items are not pressing against seams and zippers as this can reduce the effectiveness and longevity of seam sealants. 

Do’s:

• Invest in good quality waterproofing sprays and sealants. The better quality and more reputable the brand the more likely the sprays will work and less likely they are to ruin your bag with harsh chemicals. 
• Re-apply regularly. Exposure to the elements in even small doses will require spray and seam sealants to be applied regularly to ensure a waterproof backpack
• Pack thoughtfully. Once linings, dry bags and rain covers are in place it can be hard to access the contents of your bag so make sure any essentials are easily accessible at the top of your bag.
• Attach your rain cover to your backpack. Rain covers are prone to flying off in the wind, so if you intend on being in mountainous or stormy conditions use clips or ties as an extra precaution. 
• Dry out your backpack properly if it does get wet. Mould can appear over time if a backpack is not dried out properly which can perish the material, making it less waterproof in the long run. 

How do you wash a waterproof backpack?

Hand wash your backpack with warm water and a gentle detergent, do not use soap as this can damage the material and remove the waterproof spray and sealant. Using a soft brush can help to remove dust and dirt but be gentle. Dry thoroughly in the open air, avoid using a tumble dryer. 

Can you waterproof spray a backpack?

Yes! There are plenty of inexpensive waterproof sprays on the market. Ensure you follow the instructions specific to the spray and remember that sprays alone will not make your backpack 100% waterproof so should be used in conjunction with other waterproofing methods.